1.
Chromosome
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A chromosome is a DNA molecule with part or all of the genetic material of an organism. Prokaryotes usually have one single circular chromosome, whereas most eukaryotes are diploid, chromosomes in eukaryotes are composed of chromatin fiber. Chromatin fiber is made of nucleosomes, a nucleosome is a histone octamer with part of a longer DNA strand attached to and wrapped around it. Chromatin fiber, together with associated proteins is known as chromatin, chromatin is present in most cells, with a few exceptions, for example, red blood cells. Occurring only in the nucleus of cells, chromatin contains the vast majority of DNA, except for a small amount inherited maternally. Chromosomes are normally visible under a microscope only when the cell is undergoing the metaphase of cell division. Before this happens every chromosome is copied once, and the copy is joined to the original by a centromere resulting in an X-shaped structure, the original chromosome and the copy are now called sister chromatids. During metaphase, when a chromosome is in its most condensed state, in this highly condensed form chromosomes are easiest to distinguish and study. In prokaryotic cells, chromatin occurs free-floating in cytoplasm, as these cells lack organelles, the main information-carrying macromolecule is a single piece of coiled double-helix DNA, containing many genes, regulatory elements and other noncoding DNA. The DNA-bound macromolecules are proteins that serve to package the DNA, chromosomes vary widely between different organisms. Some species such as certain bacteria also contain plasmids or other extrachromosomal DNA and these are circular structures in the cytoplasm that contain cellular DNA and play a role in horizontal gene transfer. Chromosomal recombination during meiosis and subsequent sexual reproduction plays a significant role in genetic diversity. In prokaryotes and viruses, the DNA is often densely packed and organized, in the case of archaea, by homologs to eukaryotic histones, small circular genomes called plasmids are often found in bacteria and also in mitochondria and chloroplasts, reflecting their bacterial origins. Some use the term chromosome in a sense, to refer to the individualized portions of chromatin in cells. However, others use the concept in a sense, to refer to the individualized portions of chromatin during cell division. The word chromosome comes from the Greek χρῶμα and σῶμα, describing their strong staining by particular dyes, schleiden, Virchow and Bütschli were among the first scientists who recognized the structures now so familiar to everyone as chromosomes. The term was coined by von Waldeyer-Hartz, referring to the term chromatin, in a series of experiments beginning in the mid-1880s, Theodor Boveri gave the definitive demonstration that chromosomes are the vectors of heredity. His two principles were the continuity of chromosomes and the individuality of chromosomes and it is the second of these principles that was so original
2.
Bacteria
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Bacteria constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a number of shapes, ranging from spheres to rods, Bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit soil, water, acidic hot springs, radioactive waste, Bacteria also live in symbiotic and parasitic relationships with plants and animals. Most bacteria have not been characterised, and only half of the bacterial phyla have species that can be grown in the laboratory. The study of bacteria is known as bacteriology, a branch of microbiology, There are typically 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water. There are approximately 5×1030 bacteria on Earth, forming a biomass which exceeds that of all plants, Bacteria are vital in many stages of the nutrient cycle by recycling nutrients such as the fixation of nitrogen from the atmosphere. The nutrient cycle includes the decomposition of bodies and bacteria are responsible for the putrefaction stage in this process. In March 2013, data reported by researchers in October 2012, was published and it was suggested that bacteria thrive in the Mariana Trench, which with a depth of up to 11 kilometres is the deepest known part of the oceans. Other researchers reported related studies that microbes thrive inside rocks up to 580 metres below the sea floor under 2.6 kilometres of ocean off the coast of the northwestern United States. According to one of the researchers, You can find microbes everywhere—theyre extremely adaptable to conditions, the vast majority of the bacteria in the body are rendered harmless by the protective effects of the immune system, though many are beneficial particularly in the gut flora. However several species of bacteria are pathogenic and cause diseases, including cholera, syphilis, anthrax, leprosy. The most common fatal diseases are respiratory infections, with tuberculosis alone killing about 2 million people per year. In developed countries, antibiotics are used to treat infections and are also used in farming, making antibiotic resistance a growing problem. Once regarded as constituting the class Schizomycetes, bacteria are now classified as prokaryotes. Unlike cells of animals and other eukaryotes, bacterial cells do not contain a nucleus and these evolutionary domains are called Bacteria and Archaea. The ancestors of modern bacteria were unicellular microorganisms that were the first forms of life to appear on Earth, for about 3 billion years, most organisms were microscopic, and bacteria and archaea were the dominant forms of life. In 2008, fossils of macroorganisms were discovered and named as the Francevillian biota, however, gene sequences can be used to reconstruct the bacterial phylogeny, and these studies indicate that bacteria diverged first from the archaeal/eukaryotic lineage. Bacteria were also involved in the second great evolutionary divergence, that of the archaea, here, eukaryotes resulted from the entering of ancient bacteria into endosymbiotic associations with the ancestors of eukaryotic cells, which were themselves possibly related to the Archaea
3.
Host (biology)
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In biology, a host is an organism that harbors a parasitic, a mutual, or a commensal symbiont, typically providing nourishment and shelter. Examples include animals playing host to parasitic worms, cells harbouring a parasitic virus, more specifically in botany, a host plant supplies food resources and acts as a substrate for commensalist insects or other fauna. Guest is the term used for parasites, mutualists and commensals. The host range of a parasite is the collection of hosts that an organism can utilize as a partner, in the case of human parasites, the host range influences the epidemiology of the parasitism or disease. For instance, the production of antigenic shifts in Influenza A virus can result from pigs being infected with the virus from different hosts. This co-infection provides an opportunity for mixing of the viral genes between existing strains, thereby producing a new viral strain
4.
Alpha helix
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This secondary structure is also sometimes called a classic Pauling–Corey–Branson α-helix. The name 3. 613-helix is also used for type of helix, denoting the average number of residues per helical turn. Among types of structure in proteins, the α-helix is the most regular. In the early 1930s, William Astbury showed that there were changes in the X-ray fiber diffraction of moist wool or hair fibers upon significant stretching. The data suggested that the unstretched fibers had a molecular structure with a characteristic repeat of ~5.1 ångströms. Astbury initially proposed a structure for the fibers. He later joined other researchers in proposing that, the protein molecules formed a helix the stretching caused the helix to uncoil. Hans Neurath was the first to show that Astburys models could not be correct in detail, neuraths paper and Astburys data inspired H. S. Taylor, Maurice Huggins and Bragg and collaborators to propose models of keratin that somewhat resemble the modern α-helix. The pivotal moment came in the spring of 1948, when Pauling caught a cold. Being bored, he drew a polypeptide chain of roughly correct dimensions on a strip of paper and folded it into a helix, after a few attempts, he produced a model with physically plausible hydrogen bonds. Pauling then worked with Corey and Branson to confirm his model before publication. The amino acids in an α-helix are arranged in a helical structure where each amino acid residue corresponds to a 100° turn in the helix. Dunitz describes how Paulings first article on the theme in fact shows a left-handed helix, short pieces of left-handed helix sometimes occur with a large content of achiral glycine amino acids, but are unfavorable for the other normal, biological L-amino acids. The pitch of the alpha-helix is 5.4 Å, which is the product of 1.5 and 3.6, the alpha-helices can be identified in protein structure using several computational methods, one of which being DSSP. Similar structures include the 310 helix and the π-helix, the subscripts refer to the number of atoms in the closed loop formed by the hydrogen bond. Residues in α-helices typically adopt backbone dihedral angles around, as shown in the image at right, in more general terms, they adopt dihedral angles such that the ψ dihedral angle of one residue and the φ dihedral angle of the next residue sum to roughly -105°. As a consequence, α-helical dihedral angles, in general, fall on a stripe on the Ramachandran diagram. For comparison, the sum of the angles for a 310 helix is roughly -75°
5.
PH
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In chemistry, pH is a numeric scale used to specify the acidity or basicity of an aqueous solution. It is approximately the negative of the base 10 logarithm of the concentration, measured in units of moles per liter. More precisely it is the negative of the logarithm to base 10 of the activity of the hydrogen ion, solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are basic. Pure water is neutral, at pH7, being neither an acid nor a base, contrary to popular belief, the pH value can be less than 0 or greater than 14 for very strong acids and bases respectively. The pH scale is traceable to a set of standard solutions whose pH is established by international agreement, the pH of aqueous solutions can be measured with a glass electrode and a pH meter, or an indicator. In the first papers, the notation had the H as a subscript to the p, as so. The exact meaning of the p in pH is disputed, but according to the Carlsberg Foundation and it has also been suggested that the p stands for the German Potenz, others refer to French puissance. Another suggestion is that the p stands for the Latin terms pondus hydrogenii, potentia hydrogenii and it is also suggested that Sørensen used the letters p and q simply to label the test solution and the reference solution. Currently in chemistry, the p stands for decimal cologarithm of, PH is defined as the decimal logarithm of the reciprocal of the hydrogen ion activity, aH+, in a solution. P H = − log 10 = log 10 For example and this definition was adopted because ion-selective electrodes, which are used to measure pH, respond to activity. For H+ number of electrons transferred is one and it follows that electrode potential is proportional to pH when pH is defined in terms of activity. The reference electrode may be a silver chloride electrode or a calomel electrode, the hydrogen-ion selective electrode is a standard hydrogen electrode. Reference electrode | concentrated solution of KCl || test solution | H2 | Pt Firstly, the cell is filled with a solution of hydrogen ion activity. Then the emf, EX, of the cell containing the solution of unknown pH is measured. PH = pH + E S − E X z The difference between the two measured emf values is proportional to pH and this method of calibration avoids the need to know the standard electrode potential. The proportionality constant, 1/z is ideally equal to 12.303 R T / F the Nernstian slope, to apply this process in practice, a glass electrode is used rather than the cumbersome hydrogen electrode. A combined glass electrode has a reference electrode. It is calibrated against buffer solutions of hydrogen ion activity
6.
Molecule
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A molecule is an electrically neutral group of two or more atoms held together by chemical bonds. Molecules are distinguished from ions by their lack of electrical charge, however, in quantum physics, organic chemistry, and biochemistry, the term molecule is often used less strictly, also being applied to polyatomic ions. In the kinetic theory of gases, the molecule is often used for any gaseous particle regardless of its composition. According to this definition, noble gas atoms are considered molecules as they are in fact monoatomic molecules. A molecule may be homonuclear, that is, it consists of atoms of one element, as with oxygen, or it may be heteronuclear. Atoms and complexes connected by non-covalent interactions, such as hydrogen bonds or ionic bonds, are not considered single molecules. Molecules as components of matter are common in organic substances and they also make up most of the oceans and atmosphere. Also, no typical molecule can be defined for ionic crystals and covalent crystals, the theme of repeated unit-cellular-structure also holds for most condensed phases with metallic bonding, which means that solid metals are also not made of molecules. In glasses, atoms may also be together by chemical bonds with no presence of any definable molecule. The science of molecules is called molecular chemistry or molecular physics, in practice, however, this distinction is vague. In molecular sciences, a molecule consists of a system composed of two or more atoms. Polyatomic ions may sometimes be thought of as electrically charged molecules. The term unstable molecule is used for very reactive species, i. e, according to Merriam-Webster and the Online Etymology Dictionary, the word molecule derives from the Latin moles or small unit of mass. Molecule – extremely minute particle, from French molécule, from New Latin molecula, diminutive of Latin moles mass, a vague meaning at first, the vogue for the word can be traced to the philosophy of Descartes. The definition of the molecule has evolved as knowledge of the structure of molecules has increased, earlier definitions were less precise, defining molecules as the smallest particles of pure chemical substances that still retain their composition and chemical properties. Molecules are held together by covalent bonding or ionic bonding. Several types of non-metal elements exist only as molecules in the environment, for example, hydrogen only exists as hydrogen molecule. A molecule of a compound is made out of two or more elements, a covalent bond is a chemical bond that involves the sharing of electron pairs between atoms
7.
Helix
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A helix is a type of smooth space curve, i. e. a curve in three-dimensional space. It has the property that the tangent line at any point makes a constant angle with a line called the axis. Examples of helices are coil springs and the handrails of spiral staircases, a filled-in helix – for example, a spiral ramp – is called a helicoid. Helices are important in biology, as the DNA molecule is formed as two intertwined helices, and many proteins have helical substructures, known as alpha helices, the word helix comes from the Greek word ἕλιξ, twisted, curved. Helices can be either right-handed or left-handed, handedness is a property of the helix, not of the perspective, a right-handed helix cannot be turned to look like a left-handed one unless it is viewed in a mirror, and vice versa. Most hardware screw threads are right-handed helices, the alpha helix in biology as well as the A and B forms of DNA are also right-handed helices. The Z form of DNA is left-handed, the pitch of a helix is the height of one complete helix turn, measured parallel to the axis of the helix. A double helix consists of two helices with the axis, differing by a translation along the axis. A conic helix may be defined as a spiral on a conic surface, an example is the Corkscrew roller coaster at Cedar Point amusement park. A circular helix, has constant band curvature and constant torsion, a curve is called a general helix or cylindrical helix if its tangent makes a constant angle with a fixed line in space. A curve is a general helix if and only if the ratio of curvature to torsion is constant, a curve is called a slant helix if its principal normal makes a constant angle with a fixed line in space. It can be constructed by applying a transformation to the frame of a general helix. Some curves found in nature consist of multiple helices of different handedness joined together by transitions known as tendril perversions, in mathematics, a helix is a curve in 3-dimensional space. The following parametrisation in Cartesian coordinates defines a particular helix, Probably the simplest equations for one is x = cos , y = sin , z = t. As the parameter t increases, the point traces a right-handed helix of pitch 2θ and radius 1 about the z-axis, in cylindrical coordinates, the same helix is parametrised by, r =1, θ = t, h = t. A circular helix of radius a and slope b/a is described by the following parametrisation, another way of mathematically constructing a helix is to plot the complex-valued function exi as a function of the real number x. The value of x and the real and imaginary parts of the function value give this plot three real dimensions, except for rotations, translations, and changes of scale, all right-handed helices are equivalent to the helix defined above. The equivalent left-handed helix can be constructed in a number of ways, in music, pitch space is often modeled with helices or double helices, most often extending out of a circle such as the circle of fifths, so as to represent octave equivalency
8.
Catalysis
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Catalysis is the increase in the rate of a chemical reaction due to the participation of an additional substance called a catalyst. In most cases, reactions occur faster with a catalyst because they require less activation energy, furthermore, since they are not consumed in the catalyzed reaction, catalysts can continue to act repeatedly. Often only tiny amounts are required in principle, in the presence of a catalyst, less free energy is required to reach the transition state, but the total free energy from reactants to products does not change. A catalyst may participate in multiple chemical transformations, the effect of a catalyst may vary due to the presence of other substances known as inhibitors or poisons or promoters. Catalyzed reactions have an activation energy than the corresponding uncatalyzed reaction, resulting in a higher reaction rate at the same temperature. However, the mechanics of catalysis is complex. Usually, the catalyst participates in this slowest step, and rates are limited by amount of catalyst, in heterogeneous catalysis, the diffusion of reagents to the surface and diffusion of products from the surface can be rate determining. A nanomaterial-based catalyst is an example of a heterogeneous catalyst, analogous events associated with substrate binding and product dissociation apply to homogeneous catalysts. Although catalysts are not consumed by the reaction itself, they may be inhibited, deactivated, in heterogeneous catalysis, typical secondary processes include coking where the catalyst becomes covered by polymeric side products. Additionally, heterogeneous catalysts can dissolve into the solution in a system or sublimate in a solid–gas system. The production of most industrially important chemicals involves catalysis, similarly, most biochemically significant processes are catalysed. Research into catalysis is a field in applied science and involves many areas of chemistry, notably organometallic chemistry. Catalysis is relevant to aspects of environmental science, e. g. the catalytic converter in automobiles. Many transition metals and transition metal complexes are used in catalysis as well, Catalysts called enzymes are important in biology. A catalyst works by providing a reaction pathway to the reaction product. The rate of the reaction is increased as this route has a lower activation energy than the reaction route not mediated by the catalyst. The disproportionation of hydrogen peroxide creates water and oxygen, as shown below,2 H2O2 →2 H2O + O2 This reaction is preferable in the sense that the reaction products are more stable than the starting material, though the uncatalysed reaction is slow. In fact, the decomposition of hydrogen peroxide is so slow that hydrogen peroxide solutions are commercially available and this reaction is strongly affected by catalysts such as manganese dioxide, or the enzyme peroxidase in organisms
9.
Protein folding
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It is the physical process by which a polypeptide folds into its characteristic and functional three-dimensional structure from random coil. Each protein exists as a polypeptide or random coil when translated from a sequence of mRNA to a linear chain of amino acids. This polypeptide lacks any stable three-dimensional structure, as the polypeptide chain is being synthesized by the ribosome, the linear chain begins to fold into its three dimensional structure. Folding begins to occur even during translation of the polypeptide chain, amino acids interact with each other to produce a well-defined three-dimensional structure, the folded protein, known as the native state. The resulting three-dimensional structure is determined by the amino acid sequence or primary structure, the energy landscape describes the folding pathways in which the unfolded protein is able to assume its native state. Experiments beginning in the 1980s indicate the codon for an acid can also influence protein structure. The correct three-dimensional structure is essential to function, although parts of functional proteins may remain unfolded. Failure to fold into native structure generally produces inactive proteins, several neurodegenerative and other diseases are believed to result from the accumulation of amyloid fibrils formed by misfolded proteins. Many allergies are caused by folding of some proteins, because the immune system does not produce antibodies for certain protein structures. The primary structure of a protein, its linear amino-acid sequence, the amino acid composition is not as important as the sequence. The essential fact of folding, however, remains that the amino acid sequence of protein contains the information that specifies both the native structure and the pathway to attain that state. This is not to say that nearly identical amino acid sequences always fold similarly, conformations differ based on environmental factors as well, similar proteins fold differently based on where they are found. Formation of a structure is the first step in the folding process that a protein takes to assume its native structure. Formation of intramolecular hydrogen bonds provides another important contribution to protein stability, alpha helices are formed by hydrogen bonding of the backbone to form a spiral shape. The beta pleated sheet is a structure forms with the backbone bending over itself to form the hydrogen bonds. The hydrogen bonds are between the hydrogen and carbonyl carbon of the peptide bond. The alpha helices and beta pleated sheets can be amphipathic in nature, or contain a hydrophilic portion, secondary structure hierarchically gives way to tertiary structure formation. Tertiary structure of a protein involves a single chain, however
10.
AB toxin
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The AB toxins are two-component protein complexes secreted by a number of pathogenic bacteria. They can be classified as Type III toxins because they interfere with internal cell function and they are named AB toxins due to their components, the A component is usually the active portion, and the B component is usually the binding portion. The A subunit possesses enzyme activity, and is transferred to the host cell following a change in the membrane-bound transport B subunit. Among the toxins produced by certain Clostridium spp. are the binary exotoxins and these proteins consist of two independent polypeptides, which correspond to the A/B subunit moieties. The enzyme component enters the cell through endosomes produced by the oligomeric binding/translocation protein, members of the A binary toxin family include C. perfringens iota toxin Ia, C. botulinum C2 toxin CI, and Clostridium difficile ADP-ribosyltransferase. Other homologous proteins have been found in Clostridium spiroforme, members of the B binary toxin family include the Bacillus anthracis protective antigen protein, The toxin comprises three factors, the protective antigen, the oedema factor, and the lethal factor. Each is a protein of ~80kDa. PA forms the B part of the exotoxin and allows passage of the A moiety into target cells, PA protein forms the central part of the complete anthrax toxin, and translocates the B moiety into host cells after assembling as a heptamer in the membrane. The Diphtheria toxin also is an AB toxin and it inhibits protein synthesis in the host cell through phosphorylation of the eukaryotic elongation factor 2, which is an essential component for protein synthesis. The exotoxin A of Pseudomonas aeruginosa is another example of an AB toxin that targets the eukaryotic elongation factor 2, the AB5 toxins are usually considered a type of AB toxin, characterized by B pentamers. Less commonly, the term AB toxin is used to emphasize the character of the B component. This article incorporates text from the public domain Pfam and InterPro IPR003540 This article incorporates text from the public domain Pfam and InterPro IPR003896
11.
Globin
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The globins are a superfamily of heme-containing globular proteins, involved in binding and/or transporting oxygen. These proteins all incorporate the globin fold, a series of eight alpha helical segments, two prominent members include myoglobin and hemoglobin. Both of these proteins reversibly bind oxygen via a prosthetic group. They are widely distributed in many organisms, globin superfamily members share a common three-dimensional fold. This globin fold typically consists of eight alpha helices, although some proteins have additional helix extensions at their termini, since the globin fold contains only helices, it is classified as an all-alpha protein fold. The globin fold is found in its namesake globin families as well as in phycocyanins, the globin fold was thus the first protein fold discovered. The eight helices of the globin fold core share significant nonlocal structure, the helices pack together at an average angle of about 50 degrees, significantly steeper than other helical packings such as the helix bundle. Globins evolved from an ancestor and can be divided into three groups, single-domain globins, and two types of chimeric globins, flavohaemoglobins and globin-coupled sensors. Bacteria have all three types of globins, while archaea lack flavohaemoglobins, and eukaryotes lack globin-coupled sensors, several functionally different haemoglobins can coexist in the same species. Eight globins are known to occur in vertebrates, androglobin, cytoglobin, globin E, globin X, globin Y, although the fold of the globin superfamily is highly evolutionarily conserved, the sequences that form the fold can have as low as 16% sequence identity. The most famous mutation in the fold is a change from glutamate to valine in one chain of the hemoglobin molecule. This mutation creates a patch on the protein surface that promotes intermolecular aggregation. Neuroglobin belongs to a branch of the family that diverged early in evolution. Cytoglobin, an oxygen sensor expressed in multiple tissues, erythrocruorin, highly cooperative extracellular respiratory proteins found in annelids and arthropods that are assembled from as many as 180 subunit into hexagonal bilayers. Leghaemoglobin, occurs in the nodules of leguminous plants, where it facilitates the diffusion of oxygen to symbiotic bacteriods in order to promote nitrogen fixation. Non-symbiotic haemoglobin, occurs in plants, and can be over-expressed in stressed plants. Flavohaemoglobins, chimeric, with an N-terminal globin domain and a C-terminal ferredoxin reductase-like NAD/FAD-binding domain, fHb provides protection against nitric oxide via its C-terminal domain, which transfers electrons to haem in the globin. They bind oxygen, and act to initiate a response or regulate gene expression
12.
Endosome
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In cell biology, an endosome is a membrane-bound compartment inside eukaryotic cells. It is a compartment of the membrane transport pathway originating from the trans Golgi membrane. Molecules or ligands internalized from the membrane can follow this pathway all the way to lysosomes for degradation. Molecules are also transported to endosomes from the network and either continue to lysosomes or recycle back to the Golgi. Endosomes can be classified as early, sorting, or late depending on their stage post internalization, endosomes represent a major sorting compartment of the endomembrane system in cells. In HeLa cells, endosomes are approximately 500 nm in diameter when fully mature, endosomes provide an environment for material to be sorted before it reaches the degradative lysosome. For example, LDL is taken into the cell by binding to the LDL receptor at the cell surface, upon reaching early endosomes, the LDL dissociates from the receptor, and the receptor can be recycled to the cell surface. The LDL remains in the endosome and is delivered to lysosomes for processing, LDL dissociates because of the slightly acidified environment of the early endosome, generated by a vacuolar membrane proton pump V-ATPase. On the other hand, EGF and the EGF receptor have a pH-resistant bond that persists until it is delivered to lysosomes for their degradation, the mannose 6-phosphate receptor carries ligands from the Golgi destined for the lysosome by a similar mechanism. Endosomes comprise three different compartments, early endosomes, late endosomes, and recycling endosomes and they are distinguished by the time it takes for endocytosed material to reach them, and by markers such as rabs. Once endocytic vesicles have uncoated, they fuse with early endosomes, early endosomes then mature into late endosomes before fusing with lysosomes. Early endosomes mature in several ways to form late endosomes and they become increasingly acidic mainly through the activity of the V-ATPase. Many molecules that are recycled are removed by concentration in the regions of early endosomes. Loss of these tubules to recycling pathways means that late endosomes mostly lack tubules and they also increase in size due to the homotypic fusion of early endosomes into larger vesicles. Removal of recycling molecules such as receptors and mannose 6-phosphate receptors continues during this period. Finally, the endosomes lose RAB5A and acquire RAB7A, making them competent for fusion with lysosomes, fusion of late endosomes with lysosomes has been shown to result in the formation of a hybrid compartment, with characteristics intermediate of the two source compartments. For example, lysosomes are more dense than late endosomes, lysosomes reform by recondensation to their normal, higher density. However, before this happens, more late endosomes may fuse with the hybrid, some material recycles to the plasma membrane directly from early endosomes, but most traffics via recycling endosomes
. PMID 12117903.
